Alice 4061S Stereo Forward-Feed Compression Amplifier

Alice 4061S Stereo Forward-Feed Compression Amplifier

A stereo pair of audio inputs feed via XLR or balanced jack connectors via output routing relays to precision balancing transformers working in Ted Fletcher’s ‘current mode’  design which produces extremely linear output with minimal distortion. An illuminated ‘compressor’ switch operates the input relays switching the output connectors from direct (or by-pass) to compressed (compressor output). The stereo audio then enters a ‘sum and difference’ matrix where a width control affects the ‘difference’ signal and sets the stereo image width.

A feed from the ‘sum’ signal feeds filter networks and is converted to a carefully regulated DC current with controls for the speed of attack and decay. The ‘sum and difference’ (M and S) audio feeds direct to a pair of current controlled (transconductance) amplifiers which are gain controlled by the DC control current and operate in feedback around a pair of precision low distortion operational amplifiers. Buffer amplifiers convert the compressed M and S audio back to ‘left and right’, they are affected by the ‘gain make up’ control and drive specialist high quality output transformers. Balanced outputs are available on both XLR and jack connectors. Audio volume level is shown on a pair of illuminated peak programme meters developed specifically for the PYE 4061S project. An illuminated switch selects either a normal mode of left and right outputs, or the left meter showing a mono (sum) signal from a point before the output ‘gain make up’ control, and a measure of gain
reduction on the right meter.

• INPUTS 20Kohms transformer balanced, XLR and TRS jack
• OUTPUTS 56 ohms transformer balanced, XLR and TRS jack
• AMPLITUDE FREQUENCY RESPONSE +0 -0.2dB 20Hz to 20KHz
(40Hz to 10KHz within 0.06dB)
• HARMONIC DISTORTION at 1KHz at normal operating level 0.01%
2nd order 0.03% 3rd order. LF distortion dependent on release
settings
• NOISE approx. 110dB below peak operating level
• SYSTEM GAIN max 30dB.
• MAX LEVELS, INPUT +30dBu, OUTPUT +28dBu
• NORMAL OPERATING LEVEL limited to +8dB peak
• WEIGHT 2.8Kgs
• POWER 95 to 245VAC 5 watts max